1. Field of the Invention
This invention generally relates to portable heating systems and more specifically to portable radiant heaters.
2. Description of Related Art
Portable heaters are used in a number of applications to provide localized heating. For example, U.S. Pat. No. 5,437,001 (1995) to Cheney et al. discloses an upright radiant electrical heater with a reflector assembly supporting a vertically extending heating element assembly. Energy radiates in all directions in a horizontal plane so the inherent radiation pattern is onmidirectional. The reflector assembly includes heat reflective panels that redirect energy directed to the rear through an open grill at the front of the heater. A fan forces room air into the heater from below the reflector assembly upwardly through an air passage behind the assembly into an open control chamber at the top of the heater and outwardly into the room through ducts along the top front edge of the assembly. The resulting air flow assures that accessible components remain cool to the touch.
U.S. Pat. No. 5,761,377 (1998) to Wolfe et al. depicts another portable radiant heater that includes a plurality of vertically oriented, horizontally spaced quartz heating tubes. A common reflector partially surrounds the heating tubes and is configured to open at an obtuse angle at each quartz tube. The reflector is perforated to allow air to pass out from the interior of the heater. A fan moves the air for cooling purposes.
As shown in both these patents and is generally found in commercially available portable radiant heaters, the heating elements themselves are directly visible from the front exterior of the heater. Consequently various standards require an increased spacing between such heating elements and any surface which an individual can contact. In the above identified Cheney et al. patent a cylindrical grill extends partially around the heating elements. In the Wolfe et al. patent the corresponding protection is provided by a flat grill piece. This requirement for extra spacing increases the bulkiness of such space heaters by increasing the front-to-back dimension, or depth, of the portable radiant heater. That is a disadvantage in many applications.
Typically in these heating systems an individual sees only one image of each heating element which is the view of the actual heating element itself. For many individuals the result is not pleasing aesthetically.
Further in these systems heating elements radiate heat omnidirectionally so forward directed radiant energy from the heating element disperses radially. The radial dispersal dissipates energy more rapidly than a directed beam as a function of distance from the source. Energy emanating from the rear of the heating elements is reflected by the rear reflector to direct that energy into a better defined beam. Nevertheless, the forward energy continues to disperse so portable radiant heaters tend to be inefficient.